EP4046241A1

EP4046241A1 - Array antenna

Info

Publication number: EP4046241A1
Application number: EP20793760.8A
Authority: EP
Inventors: Juan Duran; Cédric MARTEL; Gaëtan PRIGENT; Olivier Pascal
Original assignee: Office National dEtudes et de Recherches Aerospatiales ONERA
Current assignee: Office National dEtudes et de Recherches Aerospatiales ONERA
Priority date: 2019-10-16
Filing date: 2020-10-07
Publication date: 2022-08-24
Anticipated expiration: 2040-10-07
Also published as: EP4046241B1; FR3102311A1; FR3102311B1; WO2021074505A1

Abstract

An array antenna (100) is formed from delay lines (L1, L2, L3...) and includes radiating elements (E11, E12, E21...) which are individually connected to line patterns (M11, M12, M21...) of the delay lines. Such an array antenna structure can be implemented by a printed circuit technology and can be used to establish radio links for data communication between a mobile carrier, such as an aircraft, and a geostationary satellite.

Description

Title: ANTENNA-NETWORK

Technical area

[0001] The present description relates to an antenna array, which may be particularly suitable for establishing a radio link in at least one of the Ku and Ka frequency bands, between a mobile carrier and a geostationary satellite.

Prior art

[0002] The communication systems designated by "SATCOM On-The-Move" make it possible to establish a radio-type communication link between a mobile carrier and a geostationary satellite. The mobile carrier can be a land vehicle, a maritime vessel or an aircraft, in particular an airplane or a drone. For civilian applications, such a system can make it possible to provide an internet connection to carrier passengers, including access to messaging services, television services, etc. For military applications, it can provide a continuous communication link between an aircraft and troops on the ground, or between an aircraft and an operational mission control post.

The use of the Ku frequency bands, between 12 GHz (gigahertz) 18 GHz, and Ka, between 26.5 GHz and 40 GHz, for such systems provides communication link rates which are higher, compared to to other frequency bands previously used. However, the Ku and Ka frequency bands require that the antennas that are used on board carriers have sufficiently high gains, including gain values that are greater than 30 dBi, where dBi is the unit of gain, in decibels per compared to an antenna which radiates uniformly in all directions of space, or "decibels relative to isotropy" in English.

[0004] Furthermore, the carrier which is equipped with the antenna being mobile, it is necessary for the antenna to be able to produce a tilting in azimuth of 0 ° (degree) to 360 °, and a sufficiently large tilting in elevation, by example from 0 ° to 60 °. Such deflections are measured with respect to a reference direction of the antenna which may be intended to be substantially parallel to the vertical direction of the place where the device is located. carrier, azimuth pertaining to rotation about the reference direction, and elevation an angle which is measured from that reference direction in a meridian plane.

[0005] In addition, it may be useful for such an antenna to be selective depending on the polarization of the radiation emitted or received. For this, the gain of the antenna must have different values depending on the polarization, with a rejection rate that is high enough for the polarization orthogonal to that used to make a communication link. The radiation polarizations involved can be, for example, the right and left circular polarizations, or two linear polarizations that are oriented perpendicular to each other.

Finally, for certain applications, the thickness of the antenna is an additional constraint, in particular when the antenna is intended to be fixed on the fuselage of an aircraft, in order to reduce air flow disturbances that can cause the antenna. Typically, thickness values that are less than a few centimeters are required for such applications on board an aircraft.

[0007] Many types of antennas have already been proposed, including antennas with fully mechanical deflection, antennas with mixed deflection, that is to say partially by orientation movement and partially by phase-shifting network effect variable, antennas with a two-dimensional array of radiating elements, antennas with an array of reflecting elements, antennas with reconfigurable materials, for example based on ferrites or liquid crystals, etc. But all these antennas only partially meet all the existing constraints, including constraints of fragility, in particular when the antenna has moving parts, size constraints, gain constraints which is sufficiently high, constraints cost, operating temperature constraints, etc.

Technical problem

[0008] From this situation, an aim of the present invention is to provide a new antenna which satisfies at least one of the aforementioned constraints to an improved extent, or which provides a compromise between some of these constraints which is improved by compared to existing antennas. In particular, the invention may aim to provide such an antenna which is suitable for providing communication links. radio in the Ku and / or Ka frequency band (s), between a mobile carrier and a geostationary satellite.

Summary of the invention

[0009] To achieve at least one of these goals or another, a first aspect of the invention provides an array antenna which comprises:

- at least one line of radiating elements, each radiating element being adapted to individually produce an emission radiation from an electrical excitation signal which is received by this radiating element;

- a control unit acting as a beam former;

- at least one delay line, which is constituted by a series assembly of line patterns, each line pattern being adapted to retransmit an electromagnetic signal which is received at input by this line pattern, with a variable delay on the basis of line within the delay line, so that the electromagnetic signal is a guided traveling wave which propagates along the delay line from a supply end of this delay line, and each line pattern being provided with at least one control input making it possible to vary the delay which is produced by this line pattern for the electromagnetic signal; and

- excitation links, coupling each line pattern of the delay line one by one to one of the radiating elements of the line of radiating elements, each excitation link being adapted to transmit to the corresponding radiating element, as an excitation electrical signal for this radiating element, an electrical signal which corresponds to a phase of the guided traveling wave as it exists at the line pattern which is coupled by the excitation link, the line d 'radiating elements and the delay line thus coupled to each other forming an antenna line.

In addition, the control unit is adapted to transmit to the at least one control input of each line pattern, an individual command which determines a value of the delay which is produced by this line pattern for the signal. electromagnetic, so that the control unit determines, by means of individual commands, a direction of emission of radiation by the array antenna. In the array antenna of the invention, each line pattern comprises at least one delay cell unit, this delay cell unit comprising at least a first variable capacitance capacitor, and at least one meander of conductive track which is combined with a second variable capacitance capacitor to produce a variable value of inductance. Then, the line pattern is arranged so that the individual command which is transmitted by the control unit to the control input of this line pattern determines capacitance values of the first and second capacitors.

Thus, the antenna which is proposed by the invention is of the antenna-array type, the direction of transmission or reception of which is selected by the individual command which is transmitted by the control unit to each pattern of delay line. The antenna can therefore not have any moving part, and can also be particularly thin, in particular with a thickness of a few centimeters or less. Furthermore, an antenna according to the invention can be manufactured using known, reliable and inexpensive technologies, such as printed circuit technologies, or PCB for "printed circuit board" in English. In particular, coplanar printed circuit technology, where a metallized surface which serves as a ground plane is coplanar with metallized portions which are intended to transmit useful signals, can be used. Finally, the absence of reconfigurable materials such as ferrites or liquid crystals, and the absence of moving parts in the antenna ensure that it is functional in a wide temperature range.

Finally, the architecture of the antenna, based on at least one delay line for which the delays which are produced by the line patterns are variable, implements a structure for addressing the electromagnetic signals to the radiating elements that is simple.

According to the invention, the array antenna further comprises a shielding structure which is arranged near the delay line, so as to at least partially obscure the radiation which is produced by the line patterns of that here, without significantly obscuring the emission radiations which are produced by the radiating elements coupled to the line patterns. Thus, spurious contributions to the radio signals emitted by the array antenna, which would be produced by the line patterns of each delay line, are reduced. In this way, the quality of the communication signals which are transmitted and / or received by the array antenna is greater. For this, each excitation link can extend through an opening in the shielding structure, this opening being located between the line pattern and the radiating element which are coupled to each other by the link d corresponding excitement.

To obtain a transmission-reception directivity for the array antenna in azimuth and in elevation, the array antenna can comprise several juxtaposed lines of radiating elements, so as to form a matrix of radiating elements, each row of radiating elements being associated with at least one delay line which is dedicated to this row of radiating elements so as to form an antenna line separate from the other antenna lines. In this case, the array antenna further comprises a phase shifter assembly which is adapted to transmit the same signal to be transmitted to the supply ends of all the delay lines, in accordance with variable phase shift values which are individually assigned to the lines. delayed by the control unit.

[0016] In preferred embodiments of the invention, at least one of the following additional characteristics can be optionally reproduced, alone or in combination of several of them:

- the delay line can be formed in at least one metallized surface of a printed circuit support, or "PCB", in particular by a coplanar printed circuit technology according to which an electrical signal transport track and an electrical ground track are formed in the same metallized surface. In this case, the array antenna thus formed may have a thickness which is less than 10 cm, preferably less than 5 cm, measured perpendicular to the printed circuit support. In addition, particularly robust and compact configurations can be obtained for the array antenna, when the radiating elements which are connected to the line patterns of the delay line by the excitation links, are carried by the same circuit carrier. printed as that of the delay line;

at least some of the excitation links can each include at least one variable coupling element, this variable coupling element having a control input adapted to receive a coupling intensity signal which is delivered by the control unit. The variable coupling element is then arranged to vary an intensity of the electrical excitation signal as received by the radiating element which is coupled by the excitation link, relative to the electromagnetic signal as transmitted in the delay line by the line pattern which is coupled by the same link excitement;

each row pattern can comprise several delay cell units, for example four delay cell units, which are assembled in series. Then, the excitation link which is coupled to this line pattern can be electrically connected to the delay line between two of the delay cell units which are successive in the line pattern, or between the last of the cell units to. delay of the line pattern and the first of the delay cell units of the next line pattern in the delay line;

- each radiating element can comprise at least one surface element, also called a pellet or “pad” in English, which is metallized or metallic, and which is coupled by continuous electrical connection or remotely coupled by electromagnetic interaction to the corresponding line pattern, so as to form the excitation link between this radiating element and this line pattern. Optionally, each radiating element can comprise several metallized or metallic surface elements, which are superimposed and all coupled to the excitation line of this radiating element, and which have different dimensions so as to produce radiation emission efficiencies which are maximum for radiation frequency values which are different between at least two of the surface elements of the same radiating element;

- the same line of radiating elements can be associated with two delay lines, so that each radiating element of the line of radiating elements is coupled to receive a first electrical excitation signal from a line pattern which belongs to a first of the two delay lines, and to simultaneously receive a second electrical excitation signal from another line pattern which belongs to the other of the two delay lines. Thus, a phase difference between the first and second electrical excitation signals which are received by the same radiating element determines a polarization of the emission radiation which is produced by that radiating element;

- a step length of the radiating elements, measured between any two radiating elements which are neighboring inside the antenna array, may be less than or equal to a smallest wavelength value in a transmission band antenna array, divided by the term (1 + sin (0max)), where 0max is a maximum value of the antenna pointing elevation angle. The radio transmission signal which is produced by the array antenna then has good homogeneity, without array lobes which would be due to spectrum aliasing; and

- each delay line can extend between its supply end and a terminal end of this delay line, the supply end being provided with an impedance matching cell, and the terminal end being provided with a termination cell which has an impedance value substantially equal to a characteristic impedance value of the delay line. In this case, and when a printed circuit technology is used to fabricate the array antenna, the impedance matching cell and the terminating cell of each delay line can be formed in the same metallized surface of circuit board that the line patterns of this delay line.

Finally, a second aspect of the invention relates to a vehicle which comprises an array antenna according to the first aspect of the invention, this array antenna being installed on board the vehicle. Such a vehicle can be, in particular, a land vehicle, a ship or an aircraft, in particular an airplane, a helicopter or a drone, including a drone with fixed airfoil or a drone of the multicopter type.

Brief description of the figures

The characteristics and advantages of the present invention will emerge more clearly in the detailed description below of non-limiting embodiments, with reference to the appended figures, among which:

[0019] [Fig. 1] is a simplified plan view of an array antenna according to the invention;

[0020] [Fig. 2] is a plan view of a delay cell unit which can be used in an array antenna according to the invention, with the circuit diagram which is equivalent to this cell;

[0021] [Fig. 3a] is a plan view of one possible embodiment for an excitation link and a radiator, intended to be coupled to a delay cell unit according to [Fig. 2];

[0022] [Fig. 3b] corresponds to [Fig. 3a] for an alternative embodiment; [0023] [Fig. 4] is a perspective view of an antenna line forming part of an antenna array conforming to [Fig. 1] - [Fig. 3b];

[0024] [Fig. 5] is a perspective view of a composite radiator which can be used in the array antenna of [Fig. 1]; [0025] [Fig. 6a] shows a possible connection method for supplying the electromagnetic signal to the delay lines of an array antenna according to the invention;

[0026] [Fig. 6b] shows another method of connection which is also possible for supplying the electromagnetic signal to the delay lines of an array antenna according to the invention; [0027] [Fig. 7a] shows another configuration which can be used for the array antenna of [Fig. 1], in order to obtain a radiation emission which is selective according to the polarization, for the embodiment of the excitation links of [Fig. 3a];

[0028] [Fig. 7b] corresponds to [Fig. 7a], for the embodiment of the excitation links of [Fig. 3b];

[0029] [Fig. 8] is a radiation pattern obtained for an array antenna according to the invention; and

[0030] [Fig. 9] illustrates a possible use of an array antenna according to the invention. Detailed description of the invention

For the sake of clarity, the dimensions of the elements which are shown in these figures do not correspond to actual dimensions, nor to actual dimensional ratios. In addition, some of these elements are represented only symbolically, and identical references which are indicated in different figures designate identical elements or which have identical functions.

The invention is now described with reference to an embodiment thereof in coplanar printed circuit technology, it being understood that a microstrip printed circuit technology, or "microstrip" in English, can also be used. Although the use of such printed circuit technologies is particularly suitable and economical, other manufacturing technologies can still be used alternatively.

The antenna array of the invention, designated by the reference 100, is formed from at least one, but preferably several antenna lines which are juxtaposed parallel to each other inside 'a plan of the antenna. Each antenna line is formed from a delay line, the latter consisting of a rectilinear chain of line patterns, all identical within a single delay line and also identical between all the lines. antenna. The line patterns are arranged in the antenna plane in a two-dimensional, preferably square, matrix, one direction of which is the direction of the length of the antenna lines, and the other direction is that of juxtaposition of the antenna lines. [Fig. 1] is a plan view of such an antenna array structure according to the invention. In this figure, L1, L2, L3 and L4 designate four delay lines which are neighboring in the array antenna 100, M11, M12 and M13 designate three successive first line patterns of the delay line L1, M21, M22 and M23 designate three successive first line patterns of the delay line L2, M31, M32 and M33 designate three successive first line patterns of the delay line L3, and M41, M42 and M43 designate three successive first line patterns of the line L4 delay. For example, each delay line can contain 41 line patterns, and the array antenna 100 can contain 42 delay lines.

Each delay line is associated with a line of radiating elements to form an antenna line, with a separate radiating element that is associated with each line pattern of the delay line. Thus, generally speaking, the radiating element Eij is supplied with an excitation signal from the line pattern Mij, where i is an integer index which identifies the delay line, i.e. Li, and j is another integer index which is equal to the sequence number of the line pattern Mij within the delay line Li. An excitation link Lij then connects an output side of the line pattern Mij to the element radiating Eij, to transmit to the latter the excitation signal which comes from the line pattern Mij. All the radiating elements Eij can be identical to each other, as can all the excitation links Lij.

We now describe possible embodiments for the components of the antenna array 100 which have just been introduced: a possible pattern structure of line, several possible models of radiating element, then two possible models of excitation link.

The upper part of [Fig. 2] shows a delay cell unit, and the lower part of the same figure shows the electrical diagram which is equivalent to this delay cell unit. On a coplanar technology printed circuit substrate, M1 and M2 denote two metallized portions which are electrically connected to each other and to an electrical ground of the array antenna 100. The portions M1 and M2 are arranged on opposite sides of metallized portions P1, P2 and P2 ', while being electrically insulated therefrom. The portions P1, P2 and P2 ’are intended to transmit an electromagnetic signal between the left and right edges of [Fig. 2], by applying a transmission delay to this signal. Thus, the electromagnetic signal propagates along the delay line which is formed by the chain of delay cell units. The portion P2 'which is on the right edge of the delay cell unit shown is continuously extended into the portion P2 which is on the left edge of the next delay cell unit in the line direction L. Alternatively, the portion P2 'extends continuously to the left edge of a segment of the delay line which is dedicated to the connection of one of the excitation links to the output of the delay cell unit shown.

In known manner, the insulation intervals between the portions M1, M2 on the one hand and the portions P1, P2 on the other hand, as well as the insulation interval between the portions P1 and P2, likewise that that between the portions P1 and P2 ', with the shape of these intervals, determine the electrical characteristics of the delay cell unit, and consequently the value of the delay produced by this delay cell unit when it transmits the electromagnetic signal from its left edge to its right edge. More precisely, the width S of the insulation gap between each of the portions P1 and P2 on the one hand and each of the portions M1 and M2 on the other hand, and the track width W, determine the characteristic impedance of sections of transmission lines T of the delay cell unit. The corresponding lengths of insulation intervals between the portions M1 / M2 and P1 / P2, or P1 / P2 ', determine the phase variations to be produced in an equivalent manner by the sections of transmission lines T, and consequently the values length to be assigned to these sections T. Moreover, the width g of the insulation intervals between the portions P1 and P2 / P2 ', as well as their length W, determine capacitance values C _se . In addition, the length l _s of meanders of the portion P1 protruding in the portions M1, M2, and the width S _s of the isolation gap in these meanders, determine an inductance value L _S h. The short-circuit connections m1 and m2 provide continuity of electrical ground function to the metallized portions M1 and M2 through the meanders which constitute the inductance L _S h. To make the values of the capacitors C _se variable and controllable, varactors V1 and V2 can be arranged to create bridges between the portions P1 and P2 / P2 '. Likewise, varactors V3 and V4 make it possible to make the value of the inductance L _S h variable and controllable. As the operation of varactor components is well known, their connections and control devices are not shown. Typically, the value of the capacitances Cse of a delay cell unit which is thus constituted can be varied by a control unit 1, denoted CTRL in [Fig. 1], between 0.3 pF (picofarad) and 1.2 pF, and the value of the inductance L _S h can be varied by the control unit 1 between 0.11 nH (nanohenry) and 0.33 nH . In the electric diagram equivalent to the delay cell unit which has just been described, the sections of transmission lines T, the capacitors of value Cse and the inductance of value L _S h are electrically connected as shown in the diagram. lower part of [Fig. 2] In the literature, such a delay cell unit is commonly called a CRLH cell, for “Composite Right Left Handed” in English. Its electrical operating principle is well known, so it is not necessary to describe it further here. The length of each CRLH cell in the direction L can be 2.7 mm (millimeter), for example.

To obtain an amplitude of variation of +/- 60 ⁰ for the direction of emission of the array antenna 100, in a plane which contains the direction L and which is perpendicular to the plane of the antenna, for a frequency of the emitted radiation which is equal to 14 GHz in the Ku band, the maximum delay which is necessary between the excitation signals which are transmitted to two successive radiating elements Eij and Ei j + 1 can be obtained from four CRLH cells as described above. These four delay cell units are arranged in series within the delay line Li, to form the line pattern Mij as considered above. Such a line pattern Mij which is made up of several delay cell units can also be called a delay line macrocell. Only one of the delay cell units of each line pattern is coupled to a radiating element through the excitation line which is dedicated to that line pattern. The length of each line pattern with four CRLH cells, in direction L, is then 4 x 2.7 mm = 10.8 mm. A condition of homogeneity of each delay line is that the length of each delay cell unit in that delay line is less than a quarter of the wavelength of the emitted radiation. Such a condition is verified for the digital values of the example described, the wavelength associated with the frequency of 14 GHz being equal to 21.4 mm.

[0039] [Fig. 3a] shows another printed circuit of coplanar technology, which constitutes the radiating element Eij and the excitation link Lij. In a simple embodiment of the radiating element Eij, the latter may consist of a metallized pellet, or “pad” in English, for example in the form of a disc 3 mm in diameter. In general, the diameter of the metallized pellet can be between 0.25l / h and 0.50l / h, where l denotes the wavelength of the emitted radiation, and n is the refractive index of the dielectric material of the printed circuit. If the frequency of the emitted radiation is 14 GHz, and the value of the refractive index n of the dielectric material is equal to 6.15 ^1/2 , then the value of 3 mm for the diameter of the metallized pellet corresponds to 0.347 l / h. Alternatively, the metallized pellet can also be in the form of a square, for example with a side still 3 mm for the value of 14 GHz of the frequency of the radiation emitted. The metallized portions Q1 and Q2 are arranged in series, the portion Q2 being intermediate between the portion Q1 and the radiating element Eij and continuous with the latter, to constitute the excitation link Lij. The metallized portion M laterally surrounds the portions Q1 and Q2. A printed circuit of the type illustrated by [Fig. 3a] is then intended to be fixed on the printed circuit of the delay line, between two delay cell units which are successive, by electrically conductive connections X1-X5, selectively after that of the delay cell units whose signal electromagnetic is intended to be transmitted to the radiating element concerned. For example, the two printed circuits of [Fig. 2] and [Fig. 3a] can be rotated in the same direction, so that the printed circuit substrate of [Fig. 3a] or intermediate between its metallized portions and those of the printed circuit of [Fig. 2] Then the conductive connection X1 connects the metallized portion Q1 to the metallized portion P2 '. Simultaneously, the conductive connections X2 and X5 connect the metallized portion M to the metallized portion M1, and the conductive connections X3 and X4 connect the metallized portion M to the metallized portion M2. Another varactor, designated by V5, can connect the metallized portions Q1 and Q2 to one another within the excitation link. Lij to adjust an amplitude of the excitation signal which is transmitted from the line pattern Mij to the radiating element Eij. Each varactor V5 has a suitable control device, and is connected so that its capacitance value is adjusted by control unit 1.

[0040] [Fig. 4] schematically shows the antenna line which is thus formed from the delay line L1. Reference 2 designates the dielectric substrate of the printed circuit in which the line patterns are formed, for example in the manner illustrated by [FIG. 1] and when each row pattern consists of four CRLH cells and a connecting segment to an excitation link. Line patterns M11, M12 and M13 are shown, with associated radiating elements E11, E12 and E13. A strip of the printed circuit which contains the delay line L1 can be enclosed in an electrically conductive formwork, to screen against the radiation that the delay line L1 could emit. For example, the conductive formwork of the delay line L1 may be composed of two formwork parts, a formwork part 21 which is arranged on the substrate 2, and a formwork part 22 which is arranged under the substrate 2, in alignment. with the formwork part 21. The radiating elements are located outside these formwork parts 21 and 22, so that the radiation which is emitted by these radiating elements is not obscured. The shuttering portions 21 and 22 thus form a shield structure which is selectively effective for the delay line L1. Openings can be provided in the formwork part 21, especially so that the shielding structure does not interfere with the electrical operation of the excitation links: the opening 011 is dedicated to the excitation link L11, the opening 012 to the excitation link L12, the opening 013 to the excitation link L13 ... The formwork parts 21 and 22 can advantageously be electrically connected to the electrical ground of the array antenna 100, and in particular the part formwork 21 can be in direct contact with the metallized portions M1, M2 and M. Possibly, the formwork parts 21 and 22 can be copper, and also be made based on printed circuits. In this case, additional printed circuit substrates which are dedicated to the formwork parts 21 and 22 can be placed on either side of the substrate 2, forming a compact stack. Metallized strips can in particular form the surfaces of the shuttering parts 21 and 22 which are parallel to the substrates, and metal studs which are arranged through the substrates can act as surfaces oriented perpendicular to the substrates for them. formwork parts 21 and 22. The contours which are indicated in broken lines in [Fig. 4] show the locations of the shield structures which are dedicated to the delay lines L2 and L3.

For an alternative embodiment of the excitation links Lij and the radiating elements Eij, the latter can be produced in the form of metallized pellets which are located on the same face of the printed circuit substrate 2 as the line patterns Mij delay lines Li. These pellets are aligned in the direction L, with a line of pellets between two delay lines Li which are adjacent. The pads are electrically isolated from each other, and electrically isolated from all the metallized portions which constitute the delay lines (P1 and P2 / P2 'in [Fig. 2]) as well as from the metallized portions of electrical ground (M1 and M2 in [Fig. 2]). [Fig. 3b] shows a possible adaptation of the excitation link Lij, which is appropriate when the radiating elements Eij thus consist of isolated metallized pellets carried by the substrate 2. The metallized portion Q2 of [Fig. 3a] can be extended in the form of a metallized line QL2, until projecting beyond the edge of the metallized pad of the radiating element Eij. The previously described assembly of the substrate of [Fig. 2] with that of [Fig. 3a] can be used for the substrate of [Fig. 3b], so that the metallized line QL2 influences remotely, by electromagnetic interaction through the printed circuit substrate of the excitation link Lij (that of [Fig. 3b]), the chip of the radiating element Eij. The position of the radiating element pad Eij, as effective when the substrates are assembled by the connections X1-X5, with respect to the metallized line QL2, is indicated by dashed lines in [Fig. 3b].

[0042] Other embodiments can still be used to make the Eij excitation links. In particular, each metallized portion Q1 can be connected to one of the metallized portions P1 or P2 / P2 'by an electrical connection which passes through the printed circuit substrate 2, or by means of a wired electrical connection and of a metallized track which are added to pass over one of the metallized portions M1 and M2. Such connection modes are commonly designated by “back biased circuit” in English and “top biased circuit”, respectively.

Possibly, each radiating element Eij can be constituted by several metallized pellets of different sizes, for example five pellets Eij ⁰ to Eij ⁴ , which are superimposed from one of them forming a basic metallized pellet, as shown in [Fig. 5]. All the metallized pads of each radiating element Eij can be electrically isolated from each other. The base pad, Eij ⁰ , can be coupled through the excitation link Lij to the line pattern Mij in any of the ways illustrated by [Fig. 3a] and [Fig. 3b]. The upper pads, Eij ¹ to Eij ⁴ in the example shown, can be supplied with an excitation signal from the base pad Eij ⁰ , remotely by electromagnetic interaction. The different pellets of the same radiating element Eij have resonant frequencies which are different, due to their respective different sizes, so that each composite radiating element which is thus constituted can be effective to emit in a widened frequency band. For example, each patch can be made on the surface of a different printed circuit substrate, and all the substrates are stacked on top of each other so as to superimpose the pads in the direction perpendicular to the substrates. Such stacks dedicated to forming the radiating elements Eij can be housed between the formwork parts 21 which are dedicated to delay lines Li which are neighboring. For the example illustrated by [Fig. 5], the pellet Eij ⁰ is in the form of a disc and carried by the substrate 2, the pellet Eij ¹ , also in the form of a disc, is carried by the substrate 21, the pellet Eij ² , still in the form of a disc, is carried by the substrate 22, the pellet Eij ³ , still in the form of a disc, is carried by the substrate 23, and finally the pellet Eij ⁴ , still in the form of a disc, is carried by the substrate 24. The respective diameters of all these pellets Eij ° -Eij ⁴ can be between 0.25l / h and 0.50l / h. In [Fig. 5], each metallized pellet and the edge of that of the printed circuit surfaces in which it is located are shown with lines of the same type.

[0044] [Fig. 6a] and [Fig. 6b] show two possible architectures for the signal supply of the delay lines by the control unit 1. A supply end of each delay line is connected by a phase shifter assembly 3 to a signal output of the unit. control 1. In the two figures, y denotes the phase of the electromagnetic signal as it arrives at the input of this phase shifter assembly 3. [Fig. 6a] corresponds to an architecture of the parallel type for the phase shifter assembly 3, in order to apply an identical phase shift Df between any two of the delay lines Li which are neighboring in the array antenna 100. In a known manner, the value of phase shift Df determines the offset of the radiation which is emitted by the array antenna 100 in a plane which is perpendicular to the lines of radiating elements. For the sake of simplicity, [Fig. 6a] is presented for four neighboring delay lines, but a person skilled in the art knows how to generalize the parallel architecture of phase shifters which is shown in this figure to the real number of antenna lines of the array antenna 100. The references 0 , Df and 2 · Df designate phase shifters which are controlled to apply delays respectively equal to 0, Df and 2 · Df to the part of the signal which they each transmit. [Fig. 6b] corresponds to [Fig. 6a] by replacing the parallel architecture of the phase shifter assembly 3 by a series architecture. In addition, to allow efficient transmission of the signal between the phase shifters and the delay lines, each delay line Li can be provided at its supply end with an impedance matching cell denoted Mi0, for i = 1 , 2, 3, ... The use of such an impedance matching cell is known to those skilled in the art, so that it is not necessary to repeat the principle here. Advantageously, each MiO impedance matching cell can be produced with the same technology as that used for the line patterns Mij, but by suitably adapting the electrical parameters of this MiO cell with respect to those of the line patterns Mij . For example, for each delay line Li, the impedance matching cell Mi0 and all the line patterns Mij, j ¹ 0, can be produced simultaneously on the same printed circuit substrate. Possibly, the MiO impedance matching cell may have a structure of the same type as the CRLH cells, but with dimensions of metallized portions and widths of the intervals between these portions which are different.

Finally, to avoid jamming of the radio signal emitted by the array antenna 100, which would be caused by a reflection of the electromagnetic signal transmitted along each delay line on the end thereof which is opposite to its supply end, each delay line Li can be terminated by a final cell MiC. In a known manner, this final cell MiC is adapted to have an input impedance which is equal to the characteristic impedance of the chain of line patterns Mij. As for the MiO impedance matching cells, the MiC final cells can advantageously be produced with the same technology as that used for the Mij line patterns, but by suitably adapting the electrical parameters of this MiC cell with respect to those of the Mij line patterns. The embodiments of [Fig. 7a] and [Fig. 7b] make it possible to emit and detect radiation selectively with respect to a polarization of this radiation which is left circular or right circular. For this, each antenna line is formed by two delay lines which are associated with the same line of radiating elements. Thus, the radiating elements Eij are simultaneously supplied with an excitation signal from the two delay lines Li and Li '. For the embodiment of [Fig. 7a], each radiating element Eij is connected to the line pattern Mij of the delay line Li by the excitation link Lij, and also connected to the line pattern Mij 'of the delay line Li' by the excitation link Lij '. The radiating element Eij can be constituted by at least one metallized disc-shaped pellet, and the excitation links Lij and Lij 'reach the circumference of the disc at two places which are angularly spaced with respect to the center of the disc. Then, excitation signals which are transmitted respectively by the excitation links Lij and Lij ', and which are identical while being out of phase by an angle controlled by the control unit 1, cause an emission of radiation which is distributed between the two left and right circular polarizations. In particular, it is possible to produce the radiation exclusively with a left or right circular polarization, when the phase shift angle is equal to the angle between the excitation links Lij and Lij 'at the edge of the disk of the element. radiating Eij, or equal to the opposite of this angle. In fact, the phase angle which is controlled by the control unit 1 is applied between the signals which are transmitted to the delay lines Li and Li ', at the level of the supply ends thereof. These delay lines Li and Li 'can be arranged on either side of the line of radiating elements Eij, as shown in [Fig. 7a] and [Fig. 7b]. Alternatively, they can be superimposed on one another on the same side of the line of radiating elements Eij. In both cases, the delay lines Li and Li 'are preferably housed separately in respective shielding structures. [Fig. 7b] is equivalent to [Fig. 7a], for the embodiment of the excitation links of [Fig. 3b].

[0047] [Fig. 8] is a diagram which shows the variations of the power density which is radiated by the array antenna 100 in a meridian plane, for two values of elevation of the transmission-reception direction: 0 ° (line curve thin) and -60 ° (curve in thick lines). The horizontal axis marks the values of the elevation angle, noted Q and measured with respect to the direction perpendicular to the antenna plane, and the vertical axis marks the values of the radiated power density, denoted D and expressed in dB (decibel). The two curves show that a directivity value of at least 33 dBi is obtained in each case. In a known manner, the directivity is defined as the maximum value of transmission power density per unit of solid angle, corresponding to the pointing direction of the array antenna 100, divided by the average value of this power density of emission over the whole complete solid angle interval, that is to say over 4 · p steradians.

Finally, [Fig. 9] shows the array antenna 100 attached to the fuselage of an airplane 101, with the printed circuit substrate 2 which is parallel to the outer surface of the fuselage at the location of the array antenna 100. The antenna -network 100 can then be used for data links between the aircraft 101 and a radio communication satellite 102, in particular for establishing internet communication links. In particular, such a data link may conform to the communication system which is known as "SATCOM On-The-Move". It is understood that the invention can be reproduced by modifying secondary aspects of the embodiments which have been described in detail above, while retaining at least some of the cited advantages. In particular, the alternative embodiments which have been described for certain components of an antenna array according to the invention can be combined with each other in multiple ways between different components. In addition, all the numerical values which have been quoted are only for illustration, and can be changed depending on the application considered. In particular, they can be adapted without difficulty for operation of the antenna in the Ka frequency band.

Claims

[Claim 1] Network antenna (100) comprising:

- at least one line of radiating elements (Eij), each radiating element being adapted to individually produce emission radiation from an electrical excitation signal which is received by said radiating element;

- a control unit (1) acting as a beam former;

- at least one delay line (Li), which is constituted by a series assembly of line patterns (Mij), each line pattern being adapted to retransmit an electromagnetic signal received at the input by said line pattern, with a delay variable to the next line pattern within the delay line, so that the electromagnetic signal constitutes a guided traveling wave which propagates along the delay line from a supply end of said line to delay, and each line pattern being provided with at least one control input for varying the delay which is produced by said line pattern for the electromagnetic signal; and

- excitation links (Lij), coupling one-to-one each line pattern (Mij) of the delay line (Li) to one of the radiating elements (Eij) of the line of radiating elements, each connection of excitation being adapted to transmit to the corresponding radiating element, as an excitation electrical signal for said radiating element, an electrical signal which corresponds to a phase of the guided traveling wave as existing at the line pattern which is coupled by said excitation link, the line of radiating elements and the delay line thus coupled to one another forming an antenna line, the control unit being adapted to transmit to the at least a control input of each line pattern, an individual control which determines a value of the delay which is produced by said line pattern for the electromagnetic signal, so that the control unit determines, through the individual controls, a direction of issue of radiation by the array antenna (100), wherein each line pattern (Mij) comprises at least one delay cell unit, said delay cell unit comprising at least a first variable capacitance capacitor (V1, V2) , and at least one conductive track meander which is combined with a second variable capacitance capacitor (V3, V4) to produce a variable inductance value, and said line pattern is arranged so that the individual control which is transmitted by the control unit (1) to the control input of said line pattern determines capacitance values of said first and second capacitors, the array antenna (100) being characterized in that it further comprises a shielding structure (21, 22) disposed near the delay line (Li), so as to at least partially obscure the radiation produced by the line patterns (Mij) of said delay line, without significantly obscuring the radiation emission which are produced by the radiating elements (Eij) coupled to said line patterns.

[Claim 2] An array antenna (100) according to claim 1, wherein each excitation link (Lij) extends through an opening (Oij) of the shield structure (21, 22), said opening being located between the line pattern (Mij) and the radiating element (Eij) which are coupled to each other by said excitation link.

[Claim 3] Antenna array (100) according to any one of the preceding claims, in which the delay line (Li) is formed in at least one metallized surface of a printed circuit support (2), in particular by a Coplanar printed circuit technology in which an electrical signal transport track and an electrical ground track are formed in a single metallized surface.

[Claim 4] An array antenna (100) according to claim 3, wherein the radiating elements (Eij) which are connected to the line patterns (Mij) of the delay line (Li) by the excitation links (Lij) , are carried by the same printed circuit support (2) as that of the delay line.

[Claim 5] An array antenna (100) according to any preceding claim, wherein at least some of the excitation links (Lij) each have at least one variable coupling element (V5), said variable coupling element. having a control input adapted to receive a coupling strength signal which is output from the control unit (1), and being arranged to vary an intensity of the electrical excitation signal as received by the radiating element ( Eij) which is coupled by said excitation link, with respect to the electromagnetic signal as transmitted in the delay line (Li) by the line pattern (Mij) which is coupled by the same excitation link.

[Claim 6] An antenna array (100) according to any one of the preceding claims, wherein each radiating element (Eij) comprises at least one metallized or metallic surface element, which is continuous electrically coupled or remotely coupled by electromagnetic interaction with the corresponding line pattern (Mij), so as to form the excitation link (Lij) between said radiating element and said line pattern.

[Claim 7] An antenna array (100) according to claim 6, wherein each radiating element (Eij) comprises several metallized or metallic surface elements (Eij ° -Eij ⁴ ), which are superimposed and all coupled to the line of. excitation (Lij) of said radiating element, and which have different dimensions so as to produce radiation emission efficiencies which are maximum for frequency values of the radiation which are different between at least two of the surface elements of the same radiating element.

[Claim 8] Antenna array (100) according to any one of the preceding claims, in which the same row of radiating elements is associated with two delay lines (Li, Li '), so that each radiating element (Eij ) of the line of radiating elements is coupled to receive a first electrical excitation signal from a line pattern (Mij) which belongs to a first (Li) of said two delay lines, and to simultaneously receive a second electrical excitation signal from another line pattern (Mij ') which belongs to the other (Li') of said two delay lines, so that a phase difference between the first and second electrical signals excitation which are received by the same radiating element determines a polarization of the emission radiation which is produced by said radiating element.

[Claim 9] Antenna array (100) according to any one of the preceding claims, comprising several juxtaposed lines of radiating elements (Eij), so as to form a matrix of radiating elements, each row of radiating elements being associated. with at least one delay line (Li) which is dedicated to said line of radiating elements so as to form an antenna line separate from the other antenna lines, the array antenna (100) further comprising an assembly phase shifter (3) suitable for transmitting the same signal to be transmitted to the supply ends of all the delay lines (Li), in accordance with variable phase shift values which are individually assigned to the delay lines by the control unit (1).

[Claim 10] An array antenna (100) according to any preceding claim, wherein a radiating element pitch length (Eij), measured between any two radiating elements which are neighboring within said array antenna. , is less than or equal to a smallest wavelength value in a transmission band of the antenna array, divided by the term (1 + sin (0max)), where 0max is a maximum angle value elevation of the antenna pointing. [Claim 11] Vehicle (101), comprising an array antenna which is in accordance with any one of the preceding claims, and which is installed on board said vehicle, said vehicle in particular being a land vehicle, a ship or an aircraft. .